\documentclass{article}
\usepackage{tikz,amsmath}
\usetikzlibrary{arrows.meta}
\usepackage[graphics,tightpage,active]{preview}
\PreviewEnvironment{tikzpicture}
\begin{document}
\begin{tikzpicture}[>=Stealth]
    \draw (0, 0) -- (3, 0);
    \foreach \x in {0, 3} {
        \draw (\x, 0) -- (\x, 0.1);
    }
    \node[above] at (1.5, 0) {$a$};
\end{tikzpicture}
\end{document}
